The approaches described in this section could be pursued but are not necessarily approaches that have previously been conceived or pursued. Therefore, unless otherwise indicated, it should not be assumed that any of the approaches described in this section qualify as prior art merely by virtue of their inclusion in this section.
With development of telephone communications, the number of parties offering services via telephone has increased. Telephone calls from these parties, such as telemarketers, pollsters, and charitable organizations, sometimes referred to as spam calls, robocalls, or junk calls, are typically unsolicited, placed in bulk and made indiscriminately. Telemarketers employ increasingly sophisticated technology to get their calls through to their target audience in spite of people's desire to be left alone. Furthermore, telemarketers can employ computers to dial a number until the call is answered, so they can automatically transfer the call to a human agent. This can be heard as a pause after the phone call is answered but before the called party can speak to the human agent.
Consumers can employ a variety of defenses against undesired callers. Some telephone services can allow anonymous call reject so that the phone does not ring if the caller Identification (ID) is blocked. Unfortunately, this strategy can prevent the receipt of calls from anyone who has set their outbound caller ID to be blocked in an attempt to maintain privacy. Legislation has been passed allowing consumers to opt out of receiving calls from telemarketers by adding their phone number to a national “do-not-call” list. However, the effectiveness of this list has been undermined by the fact that it does not apply to political organizations and charities, many telemarketers ignore the list, and the prohibition does not apply to any entity that has previously conducted business with the target. Some privacy protection techniques can employ a “whitelist” of known acceptable callers and a “blacklist” of known undesired callers, but blocking only blacklisted numbers often lets too many “junk” calls through due to the blacklist being incomplete, while allowing only calls from whitelisted numbers may be too restrictive. Moreover, managing blacklists and whitelists manually can be bothersome and often is not worth the effort.
In the meantime, computational power and network databases have advanced so much that a network operator can employ far more sophisticated and automated means for protecting privacy of the user more accurately and with minimal interaction with the user. Current methods of spam blocking are inadequate and a new approach to privacy protection is needed in the field.